She doesn't shoot something back something sarcastic and barbed, though she wants to. It's a serious pain in her ass, but she's trying to be an adult here, which honestly kind of sucks, but she's making it happen.

And let's be real, it's not like this was ever going to be a thing that thrilled him. But she tries to accept his Batty wisdom instead of just dismissing it. Maybe he means well.

"How is it rendered untenable?

She doesn't try to explain that things with Cass aren't any different, they're just more. The world didn't stop spinning, it just gained a really fantastic new moon.